#include<iostream>
#include<fstream>
using namespace std;
long P,N,p;
int puterea(long n)
{
    long b=0;
    while(n%5==0){
                    n=n/5;
                    b=b+1;
                    }
    return b;
}
int main()
{
    ifstream in("fact.in");
    ofstream out("fact.out");
    in>>P;
    if (P==0) out<<1;
    else{
         while(p<P){

                    N=N+5;
                    p=p+puterea(N);
                    }
         if (p==P) out<<N;
         else out<<-1;
         }

    in.close();
    out.close();
    return 0;
}